There are previously known apparatuses and methods for igniting arc lamps used in various applications requiring a bright light source, such as computer-generated image and slide projectors. In particular, prior igniter circuits discharge a capacitor through a spark gap that is electrically connected in series with the primary winding of a step-up transformer to produce a high-voltage pulse suitable for igniting a metal halide arc lamp.
Developing a sufficiently high voltage across the capacitor typically employs at least one of generating direct current ("DC") pulses, rectifying an alternating current ("AC") square wave, or rectifying a flyback voltage generated by an inductor. All such techniques employ relatively large and heavy magnetic components that are unduly inefficient because of parasitic winding capacitance and poor coupling between windings.
Image projectors are generally referred to as being ultra-portable if they are sufficiently small and lightweight to be carried by one. However, the above-described arc lamp igniter circuits typically have a mass of at least about 140 grams, making them one of the heaviest subassemblies employed in portable image projectors.
What is needed, therefore, is an efficient, low-mass, and compact arc lamp igniter circuit for use in "ultra-portable" projectors.